gripper_plugin.cc

#ifndef _VELODYNE_PLUGIN_HH_
#define _VELODYNE_PLUGIN_HH_

#include <gazebo/gazebo.hh>
#include <gazebo/physics/physics.hh>
#include <gazebo/transport/transport.hh>
#include <gazebo/msgs/msgs.hh>

#include <thread>
#include "ros/ros.h"
#include "ros/callback_queue.h"
#include "ros/subscribe_options.h"
#include "std_msgs/Float32.h"

namespace gazebo
{
	/// \brief A plugin to control the gripper.	
	class GripperPlugin : public ModelPlugin {
	
	/// \brief Constructor	
	public: GripperPlugin() {}

	public: virtual void Load(physics::ModelPtr _model, sdf::ElementPtr _sdf)
	{
		this->model = _model; 					// Store model pointer
		this->sdf = _sdf;					// Store sdf pointer

		this->joint1 = this->model->GetJoint("cylinder_grip1");
		this->joint2 = this->model->GetJoint("cylinder_grip2");
		this->joint3 = this->model->GetJoint("cylinder_grip3");
		this->joint4 = this->model->GetJoint("cylinder_grip4");
		this->joint5 = this->model->GetJoint("cylinder_grip5");
		this->joint6 = this->model->GetJoint("cylinder_grip6");
		
		this->pid1 = common::PID(10, 1, 1.1);
		this->pid2 = common::PID(10, 1, 1.1);
		this->pid3 = common::PID(10, 1, 1.1);
		this->pid4 = common::PID(10, 1, 1.1);
		this->pid5 = common::PID(10, 1, 1.1);
		this->pid6 = common::PID(10, 1, 1.1);

		this->model->GetJointController()->SetPositionPID(this->joint1->GetScopedName(), this->pid1);
		this->model->GetJointController()->SetPositionPID(this->joint2->GetScopedName(), this->pid2);
		this->model->GetJointController()->SetPositionPID(this->joint3->GetScopedName(), this->pid3);
		this->model->GetJointController()->SetPositionPID(this->joint4->GetScopedName(), this->pid4);
		this->model->GetJointController()->SetPositionPID(this->joint5->GetScopedName(), this->pid5);
		this->model->GetJointController()->SetPositionPID(this->joint6->GetScopedName(), this->pid6);

		this->model->GetJointController()->SetPositionTarget(this->joint1->GetScopedName(), 0);
		this->model->GetJointController()->SetPositionTarget(this->joint2->GetScopedName(), 0);
		this->model->GetJointController()->SetPositionTarget(this->joint5->GetScopedName(), 0);

		this->model->GetJointController()->SetPositionTarget(this->joint3->GetScopedName(), 0);
		this->model->GetJointController()->SetPositionTarget(this->joint4->GetScopedName(), 0);
		this->model->GetJointController()->SetPositionTarget(this->joint6->GetScopedName(), 0);
		
// ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤ ROS-related ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
		if (!ros::isInitialized())					// Initialize ros, if it has not already been initialized.
		{	
			int argc = 0;
			char **argv = NULL;
			ros::init(argc, argv, "gazebo_client",
			ros::init_options::NoSigintHandler);
		}

		this->rosNode.reset(new ros::NodeHandle("gazebo_client"));	// Create a ROS node

		ros::SubscribeOptions so1 =					// Create a ROS topic
			ros::SubscribeOptions::create<std_msgs::Float32>(
			"/" + this->model->GetName() + "/grip_rad", 1,
			boost::bind(&GripperPlugin::OnRosMsg_grip, this, _1),
			ros::VoidPtr(), &this->rosQueue1);

		ros::SubscribeOptions so2 =					// Create a ROS topic
			ros::SubscribeOptions::create<std_msgs::Float32>(
			"/" + this->model->GetName() + "/longgrip_rad", 1,
			boost::bind(&GripperPlugin::OnRosMsg_longgrip, this, _1),
			ros::VoidPtr(), &this->rosQueue2);

		this->rosSub1 = this->rosNode->subscribe(so1);			// Subscribe to the ROS topic.
		this->rosSub2 = this->rosNode->subscribe(so2);			// Subscribe to the ROS topic.

		this->rosQueueThread1 =						// Spin up the queue helper thread.
		  std::thread(std::bind(&GripperPlugin::QueueThread, this));
		this->rosQueueThread2 =						// Spin up the queue helper thread.
		  std::thread(std::bind(&GripperPlugin::QueueThread, this));
// ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤ /ROS-related ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
	}

	// -------GAZEBO-related-------
	private: physics::JointPtr joint1; 					// Pointer to joint1.
	private: physics::JointPtr joint2; 					// Pointer to joint2.
	private: physics::JointPtr joint3; 					// Pointer to joint3.
	private: physics::JointPtr joint4; 					// Pointer to joint3.
	private: physics::JointPtr joint5; 					// Pointer to joint3.
	private: physics::JointPtr joint6; 					// Pointer to joint3.
	private: common::PID pid1;						// A PID controller for joint1.
	private: common::PID pid2;						// A PID controller for joint2.
	private: common::PID pid3;						// A PID controller for joint3.
	private: common::PID pid4;						// A PID controller for joint3.
	private: common::PID pid5;						// A PID controller for joint3.
	private: common::PID pid6;						// A PID controller for joint3.
	
	private: physics::ModelPtr model; 					// Pointer to the model.
	private: sdf::ElementPtr sdf;
	
	// -------ROS-related-------
	private: std::unique_ptr<ros::NodeHandle> rosNode; 			// A node use for ROS transport
	private: ros::Subscriber rosSub1;					// A ROS subscriber
	private: ros::Subscriber rosSub2;					// A ROS subscriber
	private: ros::CallbackQueue rosQueue1;					// A ROS callbackqueue that helps process messages
	private: ros::CallbackQueue rosQueue2;					// A ROS callbackqueue that helps process messages
	private: std::thread rosQueueThread1;					// A thread the keeps running the rosQueue
	private: std::thread rosQueueThread2;					// A thread the keeps running the rosQueue

	// ROS callback function	
	public: void OnRosMsg_longgrip(const std_msgs::Float32ConstPtr &_msg)
	{
		this->model->GetJointController()->SetPositionTarget(this->joint1->GetScopedName(), _msg->data);
		this->model->GetJointController()->SetPositionTarget(this->joint2->GetScopedName(), _msg->data);
		this->model->GetJointController()->SetPositionTarget(this->joint5->GetScopedName(), _msg->data);
	}

	public: void OnRosMsg_grip(const std_msgs::Float32ConstPtr &_msg)
	{
		this->model->GetJointController()->SetPositionTarget(this->joint3->GetScopedName(), _msg->data);
		this->model->GetJointController()->SetPositionTarget(this->joint4->GetScopedName(), _msg->data);
		this->model->GetJointController()->SetPositionTarget(this->joint6->GetScopedName(), _msg->data);
	}

	// ROS helper function that processes messages
	private: void QueueThread()
	{
		static const double timeout = 0.01;
		while (this->rosNode->ok())
		{
			this->rosQueue1.callAvailable(ros::WallDuration(timeout));
			this->rosQueue2.callAvailable(ros::WallDuration(timeout));
		}
	}

  };

  // Tell Gazebo about this plugin, so that Gazebo can call Load on this plugin.
  GZ_REGISTER_MODEL_PLUGIN(GripperPlugin)
}
#endif